aggregate lab prep

8/13/2019 Aggregate Lab Prep

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CE 331 Experiment 11

Aggregate Properties

Objectives

Investigate the properties of aggregate Dry Rodded Unit Weight (DRUW) Specific Gravity Percent Absorption Density Fineness Modulus

Outline

Some concepts Experiments details:

- DRUW- specific gravity- percentage absorption- density- fineness modulus

Lab Report requirements


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UNIT WEIGHT

DENSITY

SPECIFIC GRAVITY

Some concepts : definitions

For somematerials thedensity has asingle value

For other materialsit may not be asingle values

Some Concepts - Pores

VOLUME affected by:Interparticle pores vs.

Intraparticle pores

Porosity : ratio of the volume of pores tothe total volume of particle

For porous materialsDENSITY BECOMES

FUNCTION OF THEVOLUME CONSIDERED

INTERPARTICLE POREINTRAPARTICLE

PORE

Some Concepts - Absorption

Absorption : relates to the particles abilityto take in a liquid


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Experimental details: DRUW

VOLUME = AGGREGATES+ INTRA- INTERPARTICLE

PORE VOLUME

WEIGHT = AGGREGATESWEIGHT

Aggregate usually measured and sold on a weight basis Useful when a volume is to be filled with aggregate Standard packing method ASTM Standard C-29

The procedure: Calibrate the volume of bucket

bucket

Glass plate

Tamping rod

Thermometer

Straight edg

Variation of UnitWeight of Water withTemperature (ASTM

C29)

Experimental details: DRUW

Obtain a sample of the ! to " inchsize gravel fill the bucket

Determine DRUW

Experimental details: DRUWCalculation:

SG DRUW includes interparticle pore space


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Experimental details: specific gravity

We want to quantify the interparticle porosity

ASSUMTPION!

Degree ofsaturation


MASS OF THE MODELMEASURED IN AIR

BUOYANT MASS

DRY MASS

BULK SPECIFIC GRAVITY

SG B excludes the interparticle pore space



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Experimental details: specific gravityIf you are dealing with aggregatethat has water in its pores

SSD Saturated Surface Dry

BULK SPECIFIC GRAVITYPartially saturated conditions

The rocks have been soaked for 24-hour inwater (ASTM C127)


APPARENT SPECIFIC GRAVITY

if intraparticle pore space is completelyfilled with water.

Specific Gravity- SUMMARY

SG DRUW - includes interparticle pore space SG Bulk

Excludes interparticle pore space Allows you to determine the volume occupied by just

the dry particles if you know their mass, or vice versa SG SSD -

Includes the mass of the intraparticle pore water Useful when dealing w/ aggregate that has water in its

pores SG App -

Excludes all pore space Approximates the true specific gravity of the material


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Experimental details: absorption

The procedure: Soaking of aggregates in water for 24h (done)

Approximate measure of volumeof intraparticle porosity

Importance If the volume of the pores is too great and

if filled with water, the waters expansionupon freezing will cause distress

Absorption often used to determine anaggregates ability to resist freeze/thawdamage

Example: In Indiana absorption > 5% isnot suitable for use in concrete

Experimental details: absorption

FINENESS MODULUS

A single number used to describea gradation curve (in PCC)

Uses specific sieves The larger the fineness modulus,

the more coarse the aggregate A typical fineness modulus for

fine aggregate is between 2.70and 3.00

Sieves

MechanicalshakerTypical sieve

Experimental details: particle size distribution


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no. 4 (4.75 mm) no. 8 (2.36 mm) no. 16 (1.18 mm) no. 30 (0.60 mm) no. 50 (0.30 mm) no. 100 (0.15 mm) S

i z e

i n c r e a s e s

Pan


Frequently, a special series of sieve sizes is defined for aspecific purpose

Fine aggregate for pavement

0.45 Power Maximum

Density Curve

P = % finer than the sieved = aggregate size under considerationD = maximum aggregate size to be used


WELL GRADED

Uniformly-graded Mix



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GAP-graded Mix

Influence of Gradation on Permeability

Some concepts: permeability gradation

Permeability particles ability to allow liquids topass through

Porous Concrete



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Porous Asphalt

Improved water drainage Water splash reduction (more visibility) Tire-pavement noise reduction Improved friction during wet seasons



Graphs and Tables Summary of Results Table Table(s) with data obtained Graph of Cumulative

Retained weight (%) vs.Sieve Size (log scale)

0

10

20

30

40

50

60

70

80

90

100

0.1 1

C u m u l a t

i v e

R e t a i n e

d W t . ( % )

Sieve Size (mm)

0.600.30 4.752.360.15 1.18

Discussion & Conclusion Observe and comment on trends noted from tables and

the graph Is there a noticeable trend between specific gravities?

Can you explain why?

Why are these properties important?

27

Page 2Cover page


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Table 2. Sieve Analysis

Sieve Mass Mass Mass % Cumulative

Size Sieve Sieve + Agg. Agg. Mass %

(mm) (g) (g) (g) Retained Retained

4.75

2.36

1.18

0.6

0.3

0.15

Pan

Fineness Modulus Sum(Cum%)/100


Part I Part II Part III

Sieve Cumulative

DRUW SG DRUW SG OD SG SSD SG Apparent Abs. % Size %

(pcf) (mm) Retained

4.75

2.36

1.18

0.6

0.3

0.15

PAN

FinenessModulus

Table 1. Summary of Results


Class Example

What type of gradation is this? What is the nominal maximum aggregate size? What is the maximum aggregate size?

0

10

20

30

40

50

60

70

80

90

100

0.1 1

C u m u l a t

i v e

R e t a i n e

d W t . ( % )

Sieve Size (mm)

0.600.30 4.752.360.15 1.18


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